Breeding season and nests: check first, then seal

There is one situation in which you can't just get started with bird proofing: when birds are already nesting under your panels. Then the order changes. Check first, and only then seal. That is not only the decent thing to do, it is also the law: nests that are in use may not be disturbed or removed.

When is the breeding season?

For most birds, the breeding period runs roughly from early spring to late summer. But that is a rule of thumb, not a date you can rely on. Feral pigeons, for example, breed all year round when the weather is mild, and a pair of starlings can raise two broods in one season. So the calendar doesn't tell you enough. What counts is what is under your panels at that moment.

How to check

You don't need to go up on the roof for this. At a quiet moment, preferably early in the morning, stand a few metres away and watch the bottom edge of your panels for a quarter of an hour. Look out for:

• Birds that repeatedly fly in and out at the same spot. That is almost always a nest.
• Birds flying in with twigs, moss or fluff in their beaks. Then building has just started.
• Cheeping under the panel, especially when a parent bird arrives.
• Fresh droppings or nesting material under the roof edge or in the gutter.

If you see none of this, and no nesting material either when you look under the row from the ladder, you can go ahead.

If there is a nest: wait

If there is a brood, leave it alone until the young have fledged and the nest is really no longer in use. How long that takes varies by species and by brood. Usually it becomes obvious by itself: the comings and goings stop, the cheeping ends, and nobody turns up for a few days.

Then wait a little longer. Some species use the same nest for a second brood, so if you see no activity at all for two weeks, you can be reasonably sure it's over.

If you want to know exactly what is and isn't allowed in your situation, check with your local council or a licensed pest control company. We sell brush strips; we don't give legal advice.

Sealing with birds inside is not an option

It might sound like a quick fix: seal the gap and let the birds work it out for themselves. Don't. You would be trapping animals in a space that gets very hot on a sunny day, and whatever is left behind in there you will have to clear up later anyway, which makes for a far more unpleasant job.

The best time: outside the season

The quietest time to fit bird proofing is late autumn and winter. The roof is empty then, you don't have to wait for anything, and you are ready in time for next spring. Birds start looking for their nesting sites early, and a roof that is already sealed in February won't even be considered.

Once the roof is empty

First clear out the old nesting material, otherwise it will end up trapped under your brush. Wear gloves and a dust mask while you do this; old nests are dusty. Then seal the gap with a brush that is slightly thicker than the gap, so it wedges itself in.

Not sure of your size yet? The size finder gets you to the right diameter and number of metres in a few steps.